Field
The disclosed concept relates generally to current sensing and, more particularly, to assemblies for sensing current flowing through a conductor using magnetic sensors.
Background Information
Current sensing assemblies have been employed in electrical switching apparatus, such as circuit interrupters, to measure the current flowing there through. These current sensing assemblies generally require high accuracy in order to accurately sense the current for a number of trip functions. Current sensing assemblies with a wide current range are also preferable due to the dynamic operating range of circuit interrupters.
Direct current circuit breakers, for example, have used resistive shunts to sense direct current flowing through the circuit breaker. However, the resistive shunts cause a voltage drop in the circuit breaker. Additionally, resistive shunts heat up when current is flowing through them. Both the voltage drop and the heating caused by resistive shunts are undesirable in circuit breakers.
Magnetic sensors have also been used to measure current in circuit breakers. In order to obtain a high accuracy and a wide current range from magnetic sensors, relatively complex configurations of the magnetic sensors have been used in conjunction with relatively large flux concentrators. These types of sensor assemblies are relatively large and expensive. Furthermore, the magnetic material used in flux concentrators exhibits a saturating and non-linear relationship between the magnetic force and the flux density. Typical magnetic sensors are also susceptible to external fields, and thus, are at risk of providing inaccurate results.
There is room for improvement in current sensing assemblies.
There is also room for improvement in electrical switching apparatus including current sensing assemblies.